The structure of radiative shock waves propagating through
partially ionized hydrogen gas in stellar atmospheres is discussed. Basic
equations including the radiation transfer and the method of their
self-consistent solution are described. The most striking result is that
the ratio of the radiative flux to the total energy flux of the shock wave
very rapidly enlarges with increasing upstream velocity, so that for Mach
number larger than 7, the major part of the shock energy is irreversibly
lost due to dissipation processes.
The understanding of the “missing temperature”,
called microturbulence by the astrophysicists, which appears when we want
to modelling the width of stellar line profiles, is discussed.
It is shown that the turbulence
amplification in the atmosphere of a radially pulsating star is not only
due to the global compression of the atmosphere during the
pulsation. Strong shock waves propagating from the deep atmosphere
to the very low density layers also play a role in the turbulence
variation, especially when they become very strong i.e., hypersonic.
For shocks, the predicted turbulence amplification predicted by classical
models is overestimated with respect to stellar observations
when the compression rate becomes larger than 2 which corresponds to a
limit Mach number near 2. Thus, when radiative effects take place, the
present turbulence amplification theory breaks down. A new approach is
required.

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.